<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        h2 {
            text-align: center;
        }

        .box {
            width: 600px;
            margin: 50px auto;
            display: flex;
            font-size: 25px;
            line-height: 40px;
        }

        .qs {

            width: 450px;
            height: 40px;
            color: red;

        }

        .btns {
            text-align: center;
        }

        .btns button {
            width: 120px;
            height: 35px;
            margin: 0 50px;
        }
    </style>
</head>

<body>
    <h2>随机点名</h2>
    <div class="box">
        <span>名字是：</span>
        <div class="qs">这里显示姓名</div>
    </div>
    <div class="btns">
        <button class="start">开始</button>
        <button class="end">结束</button>
    </div>

  

    <script>
        // 1. 前期准备
        // 数据数组
        const arr = ['马超', '黄忠', '赵云', '关羽', '张飞']
        let qs1=document.querySelector('.qs')
        let start=document.querySelector('.start')
        let end =document.querySelector('.end')

        // 2.给开始按钮添加事件监听
        let n=0;
        let re=-1;
       start.addEventListener('click',function(){
        n=setInterval(function(){
        let re=Math.floor(Math.random()*arr.length)
         qs1.innerHTML=arr[re]
        }, 30)
        if(arr.length===1){
            start.disabled=true;
            end.disabled=true;
        }
       })

       
        // 3.结结束按钮的添加事件监听
       end.addEventListener('click',function(){
        clearInterval(n)
        arr.splice(re,1)
       })

    </script>
</body>

</html>